Question

One mole of an ideal gas, Cp = (7/2)R and
Cv = (5/2)R, is compressed adiabatically in a
piston/cylinder device from 2 bar and 25° C to 7 bar. The process
is irreversible and requires 35% more work than a reversible,
adiabatic compression from the same initial state to the same final
pressure. What is the entropy change of the gas?